Science Musings Blog

Thursday, February 03, 2011

Zoom

Google just goes on offering us more and more of the world (the universe, really!) free of charge. Their latest is the Art Project that lets us examine in exquisite detail famous paintings from the world's great museums.

For example, since I first saw it in the flesh, I've long been fascinated by the scientific instruments on display in Hans Holbein the Younger's The Ambassadors, an enigmatic work at the National Galley in London, painted in 1533. I spent an hour last evening studying the objects arrayed between the two distinguished gentlemen.

Above, a close up of the terrestrial sphere (there is also a celestial sphere). Europe is front and center (click to enlarge). We can just glimpse the newly discovered lands across the Atlantic. Africa has been circumnavigated. The north polar region is still terra incognito.

Even in Europe, geographic details are inexactly represented. The polar circle, tropics and equator are rendered in red. The prime meridian is still -- as with Eratosthenes -- just off the Gates of Hercules (Strait of Gibraltar). Also in red is the Line of Demarcation, established by the Treaty of Tordesillas in 1494, dividing new lands of Spain from those of Portugal.

The globe indicates a reasonably accurate estimation of the size of the Earth. From the Cape Verde islands to the Nile is shown as just over 60 degrees of longitude, not too far off the actual distance.

In general, the part of the world known with some degree of accuracy is illuminated; the rest is in shadow.

From my earliest memories, there was a terrestrial globe in the house I grew up in, with all that British Empire pink and the analemma out there in the empty Pacific. I can't recall if we had a globe in the house as my kids were growing up (Tom?), but lord knows we had enough maps and atlases, including a relief map of the world that covered one whole wall of the dining room.

I invite you to go to the link above and zoom in on the celestial globe. Check out the graduations on the brass rings, in a detail that would hardly be available even in the National Gallery.